Change connection settings

Send only the settings you want to change. reject_calls declines incoming calls on this number automatically. It is off by default, because the caller sees the call declined. Each call is still announced as call.received, with rejected saying whether it was declined. proxy routes this number through its own HTTP proxy (Team plan), or removes it with null (any plan). A proxy is server (an IP address and port, not a hostname, and a public address) with an optional username and password. It is applied when the number is paired, so it can only be changed before the number is linked, or after WhatsApp has logged it out. The response shows the address and has_credentials; the username and password are never returned.